The present invention relates to novel antimony mercaptide esters of the formula ##STR2## and methods of preparing such esters.
2. Description of the Prior Art
Antimony mercaptoacid esters of the formula ##STR3## wherein R' and R" represent alkylene, arylene, alkarylene, or aralkylene groups have been prepared and used heretofore. For example, U.S. Pat. No. 4,336,168 issued Jan. 22, 1982, discloses such antimony mercaptoacid esters and their preparation by reacting a thioester with an antimony oxide compound. The reaction is illustrated in Example 1 of the patent wherein isooctyl thioglycolate is shown to have been reacted with antimony oxide to form antimony tris-(isooctyl thioglycolate) of the formula ##STR4##
Thioesters of the formula ##STR5## have heretofore been prepared by reacting an organic carboxylic acid with a mercapto alcohol in the presence of an esterification catalyst. However, such reactions often produce a number of undesirable byproducts such as thioxane and insoluble polymers of the mercapto alcohol. While special catalysts have been developed and used, they often require highly elevated temperatures and extended reaction times.
By the present invention, novel antimony mercaptide esters are provided as well as methods of preparing the esters whereby the formation of troublesome byproducts is not encountered.